OR… has any conditional stipulations that we need to be aware of, such as having to reapply?
Harvard
Stanford
Yale
Princeton
Columbia
UPenn
Brown
Dartmouth
Duke
U Chicago
UC Berkeley
Williams
Amherst
Vanderbilt
Johns Hopkins
Washington Univ St. Louis
Pomona
Univ of Denver
Univ of Colorado-Boulder
UC Berkeley will not defer enrollment unless you have required military service or in special circumstances based on a case by case review.
Most colleges have this info on their website. Best to do your own checking to make sure the info is accurate and you understand the parameters each school might impose.
If you can’t find the information on the website you can call admissions.
As others have said, check with the school, but what I’ve seen is that privates do and publics don’t.
Thank you all for your responses. As you can see, it’s a long list, so I was hoping that I didn’t have to check or call each one. 
Get your college aspiring kid to do it. Good adulting skills. 
Considering that list, you can’t put this question in other posters’ hands. You’re not asking for advice, you’re asking for answers he needs to find. And nearly all those schools look for a sort of energized kid who can. Not just what he did during high school.
@Endora - What’s “EL”?
I’m thinking that @Endora means WL or waitlist (W and E are next to each other on the keyboard). And I do know someone who got off the waitilst at Vandy and was not allowed to defer. That makes sense since schools take people off the WL to fill out their current class.
Harvard is a big proponent of gap years.
Why do you ask?
@ClarinetDad16 - My son wants to take a gap year. Fortunately, those colleges on top of his list are pro-gap, but it helps to know which ones aren’t so he can make application decisions.
Z list is Harvard. It’s about offering an admit for a year from the current fall start. In the spring of 2017, it would be an admit for fall 2018.
Whether or not a college allows a gap has to do with their own needs and policies and the case the student makes. And go by what the college itself says, not other sources.
Bottom line is that the OP (or preferably his S) will have to research the policy of each school on the list.
And Chicago. Although I’m sure other colleges have something similar.
Agreed.